Structural lithium-ion batteries with carbon fiber electrodes

ABSTRACT

Described are structural electrode and structural batteries having high energy storage and high strength characteristics and methods of making the structural electrodes and structural batteries. The structural batteries provided can include a liquid electrolyte and carbon fiber-reinforced polymer electrodes comprising metallic tabs. The structural electrodes and structural batteries provided can be molded into a shape of a function component of a device such as ground vehicle or an aerial vehicle.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. application Ser. No.15/937,279, filed Mar. 27, 2018, the entire contents of which isincorporated herein by reference.

FIELD OF THE DISCLOSURE

This disclosure relates to structural batteries having high energystorage and high strength characteristics. More particularly, thisdisclosure relates to structural lithium-ion batteries having carbonfiber-reinforced polymer electrodes, metallic tabs electrically andphysically embedded in the carbon fiber-reinforced polymer, and/or aliquid electrolyte.

BACKGROUND OF THE DISCLOSURE

Common types of energy storage devices include batteries and capacitors.Batteries use chemical reactions to store energy and traditionalcapacitors use the physical separation of electrical charges to storeenergy. Typically, a battery takes up considerable volume in a device.Accordingly, large volume batteries result in less available space forstructural components in devices that use conventional batteries.

The structure of a conventional lithium-ion battery includes anelectrolyte sandwiched between a positive and a negative electrode. Theelectrolyte allows for lithium ion migration between the two electrodesof the battery. Although lithium-ion batteries containing a liquidelectrolyte may have acceptable energy storage properties, they lacksufficient strength characteristics.

Further, battery-powered micro-unmanned aerial vehicles (UAVs) areincreasing in popularity due to their portability, low cost, andunobtrusiveness. However, micro-UAVs are greatly limited in theirmission endurance, particularly when equipped with high-powered sensorpayloads. A larger conventional battery is able to store more energy andincrease endurance in such vehicles. However, to achieve the necessaryenergy storage capacity for such vehicles, a conventional battery mustbe significantly larger and heavier than desirable.

SUMMARY OF THE DISCLOSURE

Described are structural electrodes and structural batteries that canprovide both energy to a device and structural support to a device bybeing formed into a functional component or a portion of a functionalcomponent of a device. For example, a structural battery according toembodiments described herein may be molded, shaped, or otherwisefabricated into the shape of a wing, fuselage, boom, body, door,chassis, or other structural/functional component of a device.Structural batteries described may also reduce the overall weight of adevice and improve battery life and power.

Structural electrodes and structural batteries described herein may beparticularly useful in applications including, but not limited to,communication satellites, spacecraft, ground vehicles, and/or unmannedaerial vehicles (UAV). By incorporating a structural battery into a wingcomponent or fuselage component of a UAV, or a door component or chassiscomponent of a ground vehicle, for example, endurance (range and/orflight time) may increase due to the interdependence of the subsystemweights, amount of available energy, and endurance or range. Further,structural electrodes and structural batteries may be incorporated,embedded, shaped, molded, placed inside a cavity or chamber, conformedto, or comprise a functional component of such applications.Accordingly, structural electrodes and structural batteries describedherein may improve the size, weight, and power of a device. In someembodiments, structural electrodes and structural batteries describedherein may improve the aerodynamics of a device.

Unlike conventional batteries, which are used for energy storage,structural batteries are used for providing energy and structuralsupport to a device. Currently, most energy storage devices require anadditional, separate structural component to provide necessary strengthcharacteristics. Accordingly, these combined systems (i.e., energydevice plus a separate structural component) can have a large volumeand/or mass.

However, Applicants have discovered an integrated energy and structuralsystem that uses the same material composite for both energy storage andstructural support. Applicant's integrated system can have a smallervolume and/or mass compared to a conventional energy storage devicecombined with a separate structural component.

Applicants have developed a structural battery that combines both energystorage and structural integrity into a single functional material/unit.Specifically, Applicants have developed a structural electrode that,when combined with a liquid lithium-ion electrolyte, can increase bothenergy storage and strength characteristics. Accordingly, structuralelectrodes, structural batteries, and methods of making these structuralelectrodes and structural batteries that exhibit increased energystorage and strength characteristics relative to the state-of-the-artenergy storage devices are provided herein.

In some embodiments, structural batteries and structural electrodes andmethods of making structural batteries and structural electrodes includea carbon fiber-reinforced polymer with both high energy storage and highstructural integrity characteristics. Metallic tabs may be electricallyand physically connected to the carbon fiber-reinforced polymer byembedding the metallic tabs between layers of carbon fiber sheets duringfabrication. One or more electrodes may include carbon fiber-reinforcedpolymer. Some embodiments of a structural battery may include a liquidelectrolyte.

In some embodiments, all structural support of the functional componentis provided by the structural electrode and/or structural battery, andno additional structural component is needed. In some embodiments, aportion of the structural support of the functional component isprovided by the structural electrode and/or structural battery, and someadditional structural component(s) may be needed.

In some embodiments, a method of making an electrode for a structuralbattery is provided, the method comprising: positioning one or moremetallic tabs between two or more layers of carbon fiber sheets suchthat a first portion of the one or more metallic tabs is embeddedbetween the carbon fiber sheets and a second portion of the one or moremetallic tabs extends outwardly from the carbon fiber sheets;infiltrating the carbon fiber sheets with a polymer to form a carbonfiber-reinforced polymer; molding the carbon fiber-reinforced polymerinto a shape of a functional component of a device; and abrading an edgeof the carbon fiber-reinforced polymer to expose a portion of the carbonfiber.

In some embodiments of the method of making an electrode for astructural battery, at least a portion of the shape of the functionalcomponent comprises an exterior surface of the device.

In some embodiments of the method of making an electrode for astructural battery, the exterior surface of the device is functional.

In some embodiments of the method of making an electrode for astructural battery, the exterior surface is configured to increase theaerodynamic performance of the device.

In some embodiments of the method of making an electrode for astructural battery, the device is a ground vehicle or an aerial vehicle.

In some embodiments of the method of making an electrode for astructural battery, the functional component comprises one or more of acomponent of: a wing, a boom, a body, a chassis, or a door of a device.

In some embodiments of the method of making an electrode for astructural battery, the method further comprises coating one or moresurfaces of the carbon fiber-reinforced polymer with an active material.

In some embodiments of the method of making an electrode for astructural battery, the active material comprises one or more ofgraphite, silicon, mesoporous carbon microbeads, lithium titanate,lithium cobalt oxide, lithium nickel-manganese-cobalt oxide, or lithiumiron phosphate.

In some embodiments of the method of making an electrode for astructural battery, the one or more metallic tabs comprises aluminum,copper, or nickel.

In some embodiments of the method of making an electrode for astructural battery, abrading an edge of the carbon fiber-reinforcedpolymer comprises physical abrasion or chemical exposure.

In some embodiments of the method of making an electrode for astructural battery, infiltrating the carbon fiber sheets with a polymercomprises: depositing a liquid acrylate monomer on the carbon fibersheets; and polymerizing the liquid acrylate monomer with an initiator.

In some embodiments of the method of making an electrode for astructural battery, the liquid acrylate monomer comprises ethoxylated(4) pentaerythritol tetraacrylate, tetraethylene glycol dimethacrylate,ethoxylated (30) bisphenol-A diacrylate, propoxylated (3) glyceryltriacrylate, methoxy polyethylene glycol (500) monoacrylate, or anycombination thereof.

In some embodiments of the method of making an electrode for astructural battery, the initiator is tert-butyl peroxide.

In some embodiments of the method of making an electrode for astructural battery, the initiator comprises more than 0.1 wt % of aninitiator-liquid monomer mixture.

In some embodiments of the method of making an electrode for astructural battery, the initiator comprises less than 5 wt % of aninitiator-liquid monomer mixture.

In some embodiments of the method of making an electrode for astructural battery, infiltrating the carbon fiber sheets with a polymercomprises: depositing a mixture comprising a resin and a hardener on thecarbon fiber sheets; and curing the mixture.

In some embodiments, an electrode for a structural battery is provided,the electrode comprising: one or more carbon fiber sheets; one or moremetallic tabs embedded between layers of the one or more carbon fibersheets; and a polymer, wherein the electrode is molded into a shape of afunctional component of a device.

In some embodiments of the electrode, at least a portion of the shape ofthe functional component comprises an exterior surface of the device.

In some embodiments of the electrode, the exterior surface of the deviceis functional.

In some embodiments of the electrode, the exterior surface is configuredto increase the aerodynamic performance of the device.

In some embodiments of the electrode, the device is a ground vehicle oran aerial vehicle.

In some embodiments of the electrode, the functional component comprisesone or more of a component of: a wing, a boom, a body, a chassis, or adoor of a device.

In some embodiments of the electrode, the one or more metallic tabsembedded between layers of the carbon fiber sheets comprise a firstportion embedded between the one or more carbon fiber sheets and asecond portion extending outwardly from the one or more carbon fibersheets.

In some embodiments of the electrode, the electrode further comprises asurface coating comprising an active material.

In some embodiments of the electrode, the active material comprises oneor more of graphite, silicon, mesoporous carbon microbeads, lithiumtitanate, lithium cobalt oxide, lithium nickel-manganese-cobalt oxide,or lithium iron phosphate.

In some embodiments of the electrode, the one or more metallic tabscomprises aluminum, copper, or nickel.

The electrode of claim 17, wherein an edge is abraded using physicalabrasion or chemical abrasion to expose a portion of the carbon fiber ofthe electrode.

In some embodiments of the electrode, the polymer comprises a liquidacrylate monomer and an initiator.

In some embodiments of the electrode, the initiator comprises tert-butylperoxide.

In some embodiments of the electrode, the liquid acrylate monomercomprises ethoxylated (4) pentaerythritol tetraacrylate, tetraethyleneglycol dimethacrylate, ethoxylated (30) bisphenol-A diacrylate,propoxylated (3) glyceryl triacrylate, methoxy polyethylene glycol (500)monoacrylate, or any combination thereof.

In some embodiments of the electrode, the initiator comprises more than0.1 wt % of an initiator-liquid monomer mixture.

In some embodiments of the electrode, the initiator comprises less than5 wt % of an initiator-liquid monomer mixture.

In some embodiments of the electrode, the polymer comprises a resin anda hardener.

In some embodiments, a structural battery for a device is provided, thestructural battery comprising: one or more carbon fiber-reinforcedpolymer electrodes comprising: two or more carbon fiber sheets; one ormore metallic tabs; and a polymer; and a liquid electrolyte, wherein thestructural battery is molded into a shape of a functional component of adevice.

In some embodiments of the structural battery, at least a portion of theshape of the functional component comprises an exterior surface of thedevice.

In some embodiments of the structural battery, the exterior surface ofthe device is functional.

In some embodiments of the structural battery, the exterior surface isconfigured to increase the aerodynamic performance of the device.

In some embodiments of the structural battery, the device is a groundvehicle or an aerial vehicle.

In some embodiments of the structural battery, the functional componentcomprises one or more of a component of: a wing, a boom, a body, achassis, or a door of a device.

In some embodiments of the structural battery, the structural batteryfurther comprises a surface coating on one or more surfaces of the oneor more carbon fiber-reinforced polymer electrodes.

In some embodiments of the structural battery, the surface coatingcomprises an active material comprising one or more of graphite,silicon, mesoporous carbon microbeads, lithium titanate, lithium cobaltoxide, lithium nickel-manganese-cobalt oxide, or lithium iron phosphate.

In some embodiments of the structural battery, the structural batteryfurther comprises one or more separators between two or more electrodesof the structural battery.

In some embodiments of the structural battery, the structural battery isa single-sided battery comprising layers in the order of a carbonfiber-reinforced anode, a separator, and a cathode coating on a layer ofaluminum.

In some embodiments of the structural battery, the structural battery isa double-sided battery comprising layers in the order of a carbonfiber-reinforced anode, a separator, a double-sided cathode coating, aseparator, and a carbon fiber-reinforced anode.

In some embodiments of the structural battery, the liquid electrolytecomprises one or more of lithium hexafluorophosphate, lithiumtetrafluoroborate, lithium perchlorate, lithium bis(trifluoromethylsulfonyl)imide, lithium trifluoromethanesulfonate, ethylene carbonate,ethyl methyl carbonate, propylene carbonate, dimethyl carbonate, ordiethyl carbonate.

In some embodiments of the structural battery, the one or more metallictabs comprise aluminum, copper, or nickel.

In some embodiments of the structural battery, an edge of the one ormore carbon fiber-reinforced polymer electrodes is abraded usingphysical abrasion or chemical abrasion to expose a portion of the carbonfiber of the electrode.

In some embodiments of the structural battery, the polymer comprises aliquid acrylate monomer and an initiator.

In some embodiments of the structural battery, the liquid acrylatemonomer comprises ethoxylated (4) pentaerythritol tetraacrylate,tetraethylene glycol dimethacrylate, ethoxylated (30) bisphenol-Adiacrylate, propoxylated (3) glyceryl triacrylate, methoxy polyethyleneglycol (500) monoacrylate, or any combination thereof.

In some embodiments of the structural battery, the initiator istert-butyl peroxide.

In some embodiments of the structural battery, the initiator comprisesmore than 0.1 wt % of an initiator-liquid monomer mixture.

In some embodiments of the structural battery, the initiator comprisesless than 5 wt % of an initiator-liquid monomer mixture.

In some embodiments of the structural battery, the polymer comprises aresin and a hardener.

As used herein, the singular forms “a,” “an,” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It is also to be understood that the term “and/or” as usedherein refers to and encompasses any and all possible combinations ofone or more of the associated listed items. It is further to beunderstood that the terms “includes, “including,” “comprises,” and/or“comprising,” when used herein, specify the presence of stated features,integers, steps, operations, elements, components, and/or units but donot preclude the presence or addition of one or more other features,integers, steps, operations, elements, components, units, and/or groupsthereof.

Additional advantages will be readily apparent to those skilled in theart from the following detailed description. The examples anddescriptions herein are to be regarded as illustrative in nature and notrestrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments are described with reference to the accompanyingfigures, in which:

FIG. 1 shows a structural battery in the shape of a functional componentaccording to some embodiments;

FIGS. 2A-B depict cut carbon fiber sheets according to some embodiments;

FIGS. 3A-C depict stacked carbon fiber sheets according to someembodiments;

FIGS. 4A-C depict stacked carbon fiber sheets according to someembodiments;

FIGS. 5A-B depict a tops and a side view of a metallic tab embeddedbetween carbon fiber sheets according to some embodiments;

FIGS. 6A-B show polymer infiltration of carbon fiber sheets and metallictab(s) according to some embodiments;

FIGS. 7A-C show a carbon fiber-reinforced polymer having an abraded,conductive side according to some embodiments;

FIGS. 8A-B provide a carbon fiber-reinforced polymer anode with andwithout a surface coating according to some embodiments;

FIGS. 9A-C provide examples of cathodes according to some embodiments;

FIGS. 10A-F provide various cell configurations according to someembodiments;

FIGS. 11A-C provide top views of various embodiments of cells describedherein;

FIGS. 12A-B provide side views of various embodiments of cells describedherein;

FIGS. 13A-C provide testing data for single-sided and double-sided cellsaccording to some embodiments;

FIGS. 14A-C provide testing data for cells having bare carbon fiberanodes and graphite-coated carbon fiber anodes according to someembodiments;

FIGS. 15A-C provide mechanical testing data for structural electrodesand structural batteries according to some embodiments; and

FIG. 16 shows a process diagram of a method of making a structuralelectrode and a structural battery according to some embodiments.

DETAILED DESCRIPTION OF THE DISCLOSURE

Structural electrodes and structural batteries described may be appliedto devices including, but not limited to, communication satellites,spacecraft, ground vehicles, and/or unmanned aerial vehicles (UAV). Forexample, a structural battery and/or structural electrode may beincorporated into functional components of a device such as a wingcomponent or fuselage component of a UAV, or a door component or chassiscomponent of a ground vehicle. By incorporating structural electrodesand/or structural batteries into functional components of a device, theendurance of the device (range and/or flight time) may increase due tothe interdependence of the subsystem weights, amount of availableenergy, flight endurance, and/or range of vehicle. In some embodiments,structural electrodes and/or structural batteries may improve theaerodynamic performance of a device.

Further, structural electrodes and structural batteries may beincorporated into such applications to improve the size, weight, andpower of the device. Structural electrodes and structural batteriesaccording to embodiments described herein may be incorporated, embedded,molded, and/or placed into a cavity or chamber of a functionalcomponent. In some embodiments, a functional component may be formedaround a structural electrode or battery. In some embodiments, astructural electrode or structural battery described herein may comprisea complete functional component of a device.

In some embodiments, all structural support of the functional componentis provided by the structural electrode and/or structural battery, andno additional structural component is needed. In some embodiments, aportion of the structural support of the functional component isprovided by the structural electrode and/or structural battery, and someadditional structural component(s) may be needed.

Unlike traditional batteries, which are only used for providing energy,Applicants have discovered an integrated energy and structural systemthat uses the same material composite for both energy storage andstructural support. Specifically, Applicants have developed structuralbatteries and structural electrodes and methods for making structuralbatteries and structural electrodes that can include multifunctionalmaterials that provide energy storage as well as structural integrity.For example, some embodiments may include carbon fiber-reinforcedpolymer to provide both energy storage capabilities and structuralintegrity to a structural battery. Such an integrated system can have asmaller volume and/or mass when compared to a combination ofcorresponding mono-functional elements. Additionally, not only can thestructural electrodes and structural batteries described herein havehigh structural integrity, but they can also have high energy storagecapacity.

Described herein are examples of structural batteries and electrodes andmethods for making structural electrodes and structural batteries. Thecarbon fiber-reinforced polymer may be used for electrical conductivityand structural integrity. One or more metallic tabs may be embeddedbetween layers of the carbon fiber-reinforced polymer such that the oneor more metallic tabs are physically and electrically in contact with acarbon fiber of the carbon fiber-reinforced polymer. One or more sidesof a carbon fiber-reinforced polymer may be abraded to expose a portionof the carbon fiber. The carbon fiber-reinforced polymer may be orientedsuch that an abraded edge is within the structural battery, allowing theexposed carbon fiber to interact with an electrolyte of the structuralbattery. The result of this structure is an electrode and/or batterythat can be shaped into a functional, structural component of a device.

As described in more detail below, Applicants have developed structuralelectrodes and structural batteries and methods of making structuralelectrodes and structural batteries using components that yieldacceptable energy storage and structural properties.

Various embodiments of structural electrodes and structural batteriesare described below in detail with reference to the figures includedherein.

FIG. 1 provides a schematic of drone 100 with structural energy storagecomponents according to embodiments described herein. For example,structural energy storage component 102 and 104 may comprise any one ormore features of structural electrodes and/or structural batteriesaccording to embodiments described herein. Structural energy storagecomponent 102 and/or 104 may be a specific functional component of adevice, or structural energy storage component 102 and/or 104 may beshaped, molded, conformed, embedded, placed inside a cavity or chamber,or otherwise integrated into a functional component of a device. In someembodiments, a functional component of a device may be formed aroundstructural energy storage component 102 and/or 104.

Structural energy storage component 102 may be molded or shaped into aspecific shape of a functional component of drone 100. Specifically,structural energy storage component 102 may be molded or shaped into theshape of boom 106. In some embodiments, structural energy storage 102may be conformed, embedded, or placed inside of a cavity or chamberwithin boom 106. In some embodiments, boom 106 may be formed aroundstructural energy storage 102.

Similarly, structural energy storage 104 may be molded or shaped into abody 108 of drone 100. In some embodiments, structural energy storage104 may be conformed, embedded, or placed inside of a cavity or chamberwithin body 108. In some embodiments, body 108 may be formed aroundstructural energy storage 104.

FIGS. 2A-B provide various orientations of carbon fiber sheets accordingto some embodiments described herein. Specifically, FIG. 2A depicts acarbon fiber sheet having a 0° orientation. In a rectangular carbonfiber sheet having a 0° orientation, a portion of the carbon fibers runparallel to two sides and perpendicular to two sides of the rectangularsheet. In FIG. 2A, an arrow indicates the direction of a portion ofcarbon fibers. Accordingly, in FIG. 2A, a portion of the carbon fibersrun parallel to the left and right sides of the sheet and perpendicularto the top and bottom sides of the sheet.

Conversely, FIG. 2B depicts a carbon fiber sheet having a 45°orientation. In a rectangular carbon fiber sheet having a 45°orientation, the carbon fibers run at a 45° angle to at least a firstside of the carbon fiber sheet and at a 225° angle to at least a second,parallel side of the carbon fiber sheet. In FIG. 2B, the arrow indicatesthe direction of the carbon fibers. Accordingly, in FIG. 2B, the carbonfibers run at a 45° angle to a bottom side of the carbon fiber sheet anda 225° angle to a top side of the carbon fiber sheet. Some embodimentsmay include carbon fiber sheets of other orientations as well. Forexample, some embodiments may use carbon fiber sheets of rectangular,circular, triangular, or other geometric shapes. The initial 2D shape ofthe components can be trivial and may be limited by the ability tomaintain the fiber weave of the carbon fiber sheets. In someembodiments, the carbon fiber sheets can be oriented with the fibersparallel to the edge of the sheet. In other embodiments, the carbonfiber sheets can be oriented with the fibers at a 45° angle to the edgeof the sheet. Some embodiments layer the carbon fiber sheets inalternating stacks.

FIGS. 3A-C show a 0° oriented carbon fiber sheet and a 45° orientedcarbon fiber sheet according to some embodiments. FIG. 3A illustrates a0° oriented carbon fiber sheet being stacked and aligned on top of a 45°oriented carbon fiber sheet. Some embodiments may have the 45° orientedcarbon fiber sheet stacked on top of the 0° oriented carbon fiber sheet.In some embodiments, more than two carbon fiber sheets may be used,wherein the stacking configuration alternates between 0° oriented and45° oriented carbon fiber sheets. In some embodiments, a carbon fibersheet stack may comprise only 0° orientated carbon fiber sheets or only45° oriented carbon fiber sheets. In some embodiments, a carbon fibersheet stack may include 0° oriented and/or 45° oriented carbon fibersheets stacked with other oriented carbon fiber sheets as well.

FIGS. 3B and 3C provide a top view and a side view of the 0° orientedcarbon fiber sheet stacked and aligned on top of the 45° oriented carbonfiber sheet according to some embodiments. FIG. 3B shows a top view withthe 0° oriented carbon fiber sheet on top. Accordingly, if the stackedand aligned carbon fiber sheets are the same size and perfectly alignedon top of each other, only the top sheet (in this case, the 0° orientedcarbon fiber sheet) is observable from a top perspective. However, ifthe sheets are not perfectly aligned, or a bottom sheet is larger thanthe topmost sheet, portions of bottom sheets may be observable in thisview.

FIG. 3C provides a side view of a 0° oriented carbon fiber sheet stackedon top of a 45° carbon fiber sheet. In some embodiments, a 45° orientedcarbon fiber sheet may be stacked on top of a 0° oriented carbon fibersheet.

FIG. 4A shows stacking of alternating carbon fiber sheets according tosome embodiments. Specifically, FIG. 4A shows stacking of 6 carbon fibersheets alternating between 0° oriented carbon fiber sheets and 45°oriented carbon fiber sheets. However, structural electrodes accordingto the embodiments herein may include any number of carbon fiber sheetsin any of various stacking configurations.

Determining a number of carbon fiber sheets used to fabricate the carbonfiber-reinforced polymer presents a trade-off between the energy storagecapacity and the structural integrity of the final product. For example,more carbon fiber sheets may increase the structural integrity of theelectrode, but detract from the amount of energy stored per unit weight(or volume) of the electrode. Conversely, less carbon fiber sheets mayincrease the energy storage capabilities of the electrode, yet decreasethe structural integrity of the electrode.

In some embodiments, more than one carbon fiber sheet may be used, morethan two sheets may be used, more than three sheets may be used, or morethan four sheets may be used. In some embodiments, less than ten carbonfiber sheets may be used, less than eight sheets may be used, less thansix sheets may be used, or less than four sheets may be used. In someembodiments, two pieces of carbon fiber sheets may be used.

Additionally, as described above, any stacking configuration of carbonfiber sheets may be used, including but not limited to, only 0° orientedsheets, only 45° oriented sheets, alternating 0° and 45° orientedsheets, a mixed configuration of 0° oriented sheets and 45° orientedsheets such as A-B-B-A-B-B, A-B-A-C-A-B-A-C, A-A-B-B-A-A-B-B, etc., andany other combination of orientations recognized by one having skill inthe art.

FIG. 4B shows a top view of the stacked configuration of carbon fibersheets depicted in FIG. 4A. Similarly to FIG. 3B, and described in moredetail above, the top view may vary according to the size and stackingconfiguration of the carbon fiber sheets.

FIG. 4C provides a side view of the stacked configuration of carbonfiber sheets depicted in FIG. 4A. The stacking configuration of thecarbon fiber sheets may be alternating, as shown in FIG. 4B, or thecarbon fiber sheets may be stacked according to another pattern (i.e.,A-B-B-A-B-B, A-B-A-C-A-B-A-C, A-A-B-B-A-A-B-B, etc.).

In some embodiments, one or more metallic tabs may be placed betweenlayers of carbon fiber sheets. For example, FIG. 5 shows metallic tab550 placed between two carbon fiber sheets. Metallic tab 550 may includetwo portions—an embedded portion 560 and an outwardly extending portion558. Embedded portion 560 of metallic tab 550 may be located between twoor more carbon fiber sheets. In FIG. 5B, embedded portion 560 ofmetallic tab 550 is shown located between two carbon fiber sheets. Insome embodiments, embedded portion may be no less than 1 cm in length,or a length of at least 1 cm of metallic tab 550 may extend inwardlybetween two or more carbon fiber sheets. In some embodiments, embeddedportion 560 may be greater than 1 cm long. In some embodiments, embeddedportion 560 may be greater than 1.2 cm, greater than 1.4 cm, greaterthan 1.6 cm, greater than 1.8 cm, greater than 2.0 cm, greater than 2.5cm, greater than 3.0 cm, greater than 5.0 cm, or greater than 10.0 cmlong. In some embodiments, embedded portion 560 may be less than 10.0cm, less than 8.0 cm, less than 5.0 cm, less than 3.0 cm, less than 2.5cm, less than 2.0 cm, or less than 1.5 cm long.

In some embodiments, adhesive Kapton tape 552 may be applied to bothsides of outwardly extending portion 558 of metallic tab 550 to preventepoxy/polymer form adhering to metallic tab 550. However, Kapton tape552 is only one method of preventing epoxy/polymer from adhering tometallic tab 550. In some embodiments, other types of physical mechanismmay be used to prevent the epoxy from adhering to metallic tab 550. Insome embodiments, chemical exposure may be used to remove any epoxy thatadheres to metallic tab 550.

FIG. 5A shows a top view of a stacked configuration of carbon fibersheets placed on PTFE (polytetrafluoroethylene) sheet 556. A carbonfiber sheet stack-and-PTFE sheet assembly is placed on glass plate 554.FIG. 5B provides a side view of a stacked configuration of carbon fibersheets 562 including metallic tab 550. Carbon fiber sheet stack 562 isprovided on PTFE sheet 556, which is then placed on glass plate 554.

In some embodiments, a non-flat structural energy storage component maybe desired. For example, some embodiments include a structural energystorage component formed in the shape of a functional component of adevice. Accordingly, some embodiments may include forming the structuralenergy storage component in the shape of a wing component, fuselagecomponent, boom component, door component, chassis component, etc. Suchportions of functional components and/or the entire component itself maynot comprise a completely flat surface. Accordingly, instead of formingthe structural energy storage component on a flat PTFE sheet and glassplate, some embodiments may form structural energy storage componentsusing molds. For example, a structural energy storage component(electrode and/or battery) according to some embodiments describedherein may be molded or formed in a curved shape according to afunctional component of a device. In FIG. 1 , structural storage energydevices 102 and 104 may be curved according to the design of boom 106and body 108 with which they correspond. Accordingly, a mold ofappropriate shape, curvature, design, etc. may be used instead of theflat glass plate of FIGS. 5A and 5B. Similarly, an appropriate moldrelease agent may be used instead of the PTFE sheet of FIGS. 5A and 5B.

FIGS. 6A and 6B show the fabrication of a carbon fiber-reinforcedpolymer according to embodiments described herein. FIG. 6A shows polymer664 infiltration of the carbon fiber sheet stack 662 and metallic tab650. As described in more detail below, polymer 664 may be aresin/hardener combination or a monomer/initiator combination. Polymer664 infiltrates the carbon fiber sheet stack-and-metallic tab assemblyand may fill any crevices within or between carbon fiber sheets. FIG. 6Bshows a side view of the assembly after polymer 664 infiltration. Insome embodiments, when the resin/hardener or monomer/initiator 664 iscuring, a second PTFE sheet 656 and glass plate 654 may be placed on topof the assembly. Weights 666 may be placed on top of the second PTFEsheet 656 and glass plate 654 to form a flat structural electrode. Insome embodiments, as discussed above, a structural energy storagecomponent that is not flat may be molded or formed. For example, acurved or otherwise non-flat mold may be used along with a moldreleasing agent in place of the PTFE sheet 656 and glass plate 654.Thus, a structural energy storage component according to embodimentsdescribed herein may be fabricated according to the shape of afunctional component of a device, as described. After curing, the Kaptontape may be removed to expose metallic tab 650. In some embodiments,another physical mechanism and/or chemical mechanism for preventingepoxy/polymer 664 to adhere to metallic tab 650 may be used. In someembodiments, a physical mechanism or a chemical mechanism known in theart may be used to remove any epoxy/polymer 664 from metallic tab 650that may have adhered during polymer 664 infiltration.

FIGS. 7A-7C demonstrate abrading a side of the carbon fiber-reinforcedpolymer according to some embodiments described herein. Any method ofabrasion or polymer-removal method known in the art may be used toremove any epoxy/polymer formed on a side of the carbon fiber-reinforcedpolymer. Because polymer 764 is insulating, removing any polymer on atleast one side of the carbon fiber-reinforced polymer is necessary toexpose a portion of the conductive carbon fiber, which will allow theelectrons to travel from metallic tab 750, through the carbon fiber ofthe carbon fiber-reinforced polymer 768, and to the surface coating orthe electrode-electrolyte interface of a structural battery and viceversa. Accordingly, one or more sides of the carbon fiber-reinforcedpolymer to be abraded may at least be a side that will be exposed toelectrolyte within a structural battery. For example, FIG. 7B indicatesabrasion of a top side of carbon fiber-reinforced polymer 768. In someembodiments, at least a portion of a top side of carbon fiber-reinforcedpolymer 768 may be within a structural battery and configured tointeract with an electrolyte of the structural battery.

FIG. 7C is a photo of a carbon fiber-reinforced electrode according tosome embodiments described herein. The metallic tab of FIG. 7C comprisescopper.

FIGS. 8A and 8B provide side views of at least two different carbonfiber-reinforced anodes according to some embodiments described herein.The anodes of FIGS. 8A and 8B may be used in a single-sided or in adouble-sided structural battery cell.

For example, FIG. 8A shows a side view of carbon fiber-reinforcedpolymer anode 868 including one or more carbon fiber sheets, one or moremetallic tab 850, and infiltrating polymer 864. In some embodiments, acarbon fiber-reinforced anode may additionally include surface coating870. For example, FIG. 8B shows a carbon fiber-reinforced anodecomprising a surface coating 870 on the abraded side of the assembly. Asurface coating of a carbon fiber-reinforced anode may comprise anyactive material known in the art including, but not limited to,graphite, silicon, mesoporous carbon microbeads, and/or lithiumtitanate.

FIGS. 9A-9C provide side views of at least three different cathodesaccording to some embodiments described herein. For example, FIG. 9Ashows a cathode for a single-sided structural battery cell (that doesnot comprise a carbon fiber-reinforced polymer) according to someembodiments. The cathode of FIG. 9A shows a layer of cathode coating ona layer of aluminum foil. In some embodiments, metallic tab 950 may bespot-welded to the cathode.

FIG. 9B shows a carbon fiber-reinforced polymer cathode for asingle-sided call according to some embodiments. In FIG. 9B, metallictab 950 may be embedded between two or more carbon fiber sheets duringfabrication of the carbon fiber-reinforced polymer cathode 968.Additionally, surface coating 970 may be applied to a conductive (orabraded) side of the carbon fiber-reinforced polymer. Surface coating970 of a carbon fiber-reinforced polymer cathode may include, but is notlimited to, lithium cobalt oxide, lithium nickel-manganese-cobalt oxide,and/or lithium iron phosphate.

FIG. 9C shows a cathode for a double-sided structural battery cell (thatdoes not comprise a carbon fiber-reinforced polymer) according to someembodiments. In some embodiments, as described above, metallic tab 950may be spot-welded to the cathode. Further, some embodiments of cathodesdescribed herein may comprise a surface coating on more than oneconductive side of the electrode. For example, FIG. 9C depicts surfacecoating 970 on both a top and a bottom side of the aluminum foil(cathode material). A surface coating of a cathode may include lithiumcobalt oxide, lithium nickel-manganese-cobalt oxide, and/or lithium ironphosphate.

FIGS. 10A-10F provide various structural battery configurationsaccording to some embodiments described herein. Specifically, FIGS.10A-10D show various configurations of single-sided structural batterycells. FIGS. 10E and 10F show different configurations of double-sidedstructural battery cells.

FIG. 10A shows a single-sided structural battery cell including onecarbon fiber-reinforced polymer electrode (an anode). A cathode of someembodiments may be any conventional cathode known in the art. Separatorsheet 1072 may be layered between carbon fiber-reinforced polymer anode1074 and conventional cathode 1076. Both carbon fiber-reinforced anode1074 and conventional cathode 1076 may include at least one metallic tab1050. Some embodiments of a conventional cathode include spot-weldingmetallic tab 1050 to the cathode. Some embodiments of a carbonfiber-reinforced polymer anode include embedding a portion of metallictab 1050 between two or more layers of carbon fiber sheets.

FIG. 10B provides a single-sided structural battery cell including twocarbon fiber-reinforced polymer electrodes. The single-sided structuralbattery cell of FIG. 10B, may include carbon fiber-reinforced polymeranode 1074 and carbon fiber-reinforced polymer cathode 1078. Separatorsheet 1072 is layered between carbon fiber-reinforced polymer anode 1074and carbon fiber-reinforced polymer cathode 1078. Additionally, carbonfiber-reinforced polymer cathode 1078 may include a surface coating on aconductive side of the structural battery cell. Both carbonfiber-reinforced anode 1074 and carbon fiber-reinforced polymer cathode1078 may include at least one metallic tab 1050.

FIG. 10C shows a single-sided structural battery cell according to someembodiments described herein. The structural battery cell of FIG. 10Cmay include a single carbon fiber-reinforced polymer electrode (ananode) 1074 and conventional cathode 1076. Separator sheet 1072 may belayered between carbon fiber-reinforced polymer electrode 1074 andconventional cathode 1076. However, unlike the structural battery celldepicted in FIG. 10A, the structural battery cell of FIG. 10C includesboth a cathode surface coating and an anode surface coating.Accordingly, separator sheet 1072 may be layered directly adjacent to,and in contact with, a surface coating of conventional cathode 1076 anda surface coating of carbon fiber-reinforced polymer anode 1074. Bothcarbon fiber-reinforced anode 1074 and conventional cathode 1076 mayinclude at least one metallic tab 1050.

FIG. 10D shows a single-sided structural battery cell according to someembodiments described herein. For example, the embodiment depicted inFIG. 10D includes both a carbon fiber-reinforced polymer anode 1074 anda carbon fiber-reinforced polymer cathode 1078. Unlike the structuralbattery cell of FIG. 10B, which only includes a surface coating oncarbon fiber-reinforced cathode 1078, the structural battery cell ofFIG. 10D may include a surface coating on both carbon fiber-reinforcedpolymer anode 1074 and carbon fiber-reinforced polymer cathode 1076.

FIG. 10E provides a double-sided structural battery cell according tosome embodiments described herein. Specifically, FIG. 10E shows adouble-sided structural battery cell that may include two or more carbonfiber-reinforced polymer anodes 1074 and conventional cathode 1076.Conventional cathode 1076 may include a surface coating on both a topsurface and a bottom surface. Additionally, the electrodes—conventionalcathode 1076 and two or more carbon fiber-reinforced anodes 1074—mayinclude at least one metallic tab 1050. Metallic tabs 1050 of carbonfiber-reinforced polymer anodes 1074 may be embedded between two or morelayers of carbon fiber sheets during fabrication of the carbonfiber-reinforced polymer. Metallic tab 1050 of conventional cathode 1076may be spot-welded to the cathode material. Further, one or moreseparator sheets 1072 may be layered between cathode 1076 and each anode1074. However, because the carbon fiber-reinforced polymer anodes 1074of FIG. 10E may not include a surface coating, separator sheet 1072 maybe layered directly adjacent to, and in contact with, carbonfiber-reinforced anodes 1074.

FIG. 10F provides a double-sided structural battery cell according tosome embodiments described herein. Specifically, FIG. 10F shows adouble-sided structural battery cell that may include two or more carbonfiber-reinforced polymer anodes 1074 that each may include at least oneembedded metallic tab 1050. Metallic tab 1050 may be layered between twoor more carbon fiber sheets during fabrication. The structural batterycell of FIG. 10F may also include a double-sided conventional cathode1076 that may have a metallic tab 1050. Metallic tab 1050 may bespot-welded to the cathode material during fabrication. Further, anodes1074 and cathode 1076 may include a surface coating on a conductive sideof the electrode. Because cathode 1076 is a double-sided conventionalcathode, it may include a surface coating on both a top and a bottomsurface. Carbon fiber-reinforced anodes 1074 may include a surfacecoating on a conductive and/or an abraded side of the anode. Separatorsheets 1072 may be layered between carbon fiber-reinforced anodes 1074and double-sided conventional cathode 1076. Because both carbonfiber-reinforced anodes 1074 and conventional cathode 1076 may includesurface coatings, separator sheets 1072 may be layered between theelectrodes and surface coatings such that separator sheets 1072 areadjacent to, or in contact with, surface coatings of the proximateelectrodes.

FIGS. 11A-11C provide top views of structural battery cells according tosome embodiments described herein. FIG. 11A shows a top view of stackedbattery components. For example, the battery components stack of FIG.11A shows a carbon fiber-reinforced polymer cathode as an uppermostlayer, indicated by the carbon fiber sheet and aluminum metallic tab1180. Aluminum metallic tab 1080 may be embedded between layers ofcarbon fiber sheets during fabrication of the cathode. Separator sheet1172 may be layered between an uppermost carbon fiber-reinforced polymercathode 1078 and a carbon fiber-reinforced polymer anode. Nickel orcopper metallic tab 1182 may be embedded between carbon fiber layers ofa carbon fiber-reinforced polymer anode.

FIG. 11B shows a top view of a structural battery cell within anenvironmental barrier 1184. The structural battery cell may include atleast two metallic tabs 1050—aluminum tab 1180 for a cathode and nickelor copper tab 1182 for an anode. In some embodiments, environmentalbarrier 1184 may include a sealant or coating material that may protectthe structural battery cell from water and air. In some embodiments,environmental barrier 1184 may be a laminated aluminum pouch thatprotects structural battery cell from water and air. FIG. 11C provides aphotograph of a structural battery cell within an aluminum pouch thatprotects the structural battery cell from the elements.

FIGS. 12A and 12B provide side views of different embodiments ofenvironmental barrier 1284. For example, FIG. 12A shows a double-sidedstructural battery cell protected from the elements by a laminatedaluminum pouch as environmental barrier 1284. Metallic tabs 1250 mayextend through the aluminum pouch and may extend outwardly to anexterior area of the aluminum pouch surrounding the structural batterycell. The structural battery cell within the aluminum pouch may compriseany one or more features according to the embodiments of structuralenergy storage components described herein.

FIG. 12B shows a double-sided structural battery cell having animpermeable sealant and/or coating as environmental barrier 1284. Thisimpermeable sealant and/or coating may be any suitable barrier layer.Further, like the structural battery cell of FIG. 12A, metallic tabs1250 extend through the impermeable sealant and/or coating layer and mayextend outwardly to an exterior area of the layer. The structuralbattery cell within the impermeable sealant and/or coating layer maycomprise a configuration according to any of the embodiments ofstructural energy storage components described herein.

FIG. 16 provides a process 1600 demonstrating a method of making astructural energy storage component according to some embodiments. Forexample, a structural electrode may be formed by positioning one or moremetallic tabs between two or more layers of carbon fiber sheets 1690,infiltrating the carbon fiber sheets with a polymer to form a carbonfiber-reinforced polymer 1692, molding the carbon fiber-reinforcedpolymer into a shape of a functional component of a device 1694, and/orabrading an edge of the carbon fiber-reinforced polymer to expose aportion of the carbon fiber 1696. A structural battery may include atleast one additional step that includes layering a separator and/or anelectrolyte between two or more electrodes 1698, at least one of whichis a carbon fiber-reinforced polymer electrode. The method-making steps1690, 1692, 1694, 1696, and 1698 may be performed in any sequence and incombination with any other steps for making an electrode and/or abattery known in the art.

Fabrication Methods and Techniques for Current Collectors and Electrodes

In some embodiments, electrodes may serve as a structural material aswell as an active ion material or current collector. An electrode may befabricated separately and/or prior to fabricating a structural battery.A method of making an electrode disclosed herein can include providingcarbon fiber sheets; embedding one or more metallic tabs between layersof the carbon fiber sheets; infiltrating the carbon fiber sheets with apolymer to form a carbon fiber-reinforced polymer; and abrading a sideof the carbon fiber-reinforced polymer sheet to expose the conductivecarbon fiber. The following sections describe various materials andsteps that can be included in making an electrode for a structuralbattery.

Carbon Fiber-reinforced Polymer: In some embodiments, carbon fibersheets can be used to form the base of the electrodes. Carbon fibersheets may be cut into a desired shape and/or orientation. For example,carbon fiber sheets may be cut in a 0° orientation (with the carbonfibers parallel to an edge) and/or a 45° orientation (with the carbonfibers at a 45° angle to an edge).

The carbon fiber sheets may be oriented in various ways. In someembodiments, a current collector may include both 0° orientation and 45°orientation sheets. In some embodiments, a current collector may includeonly 0° orientation or only 45° orientation carbon fiber sheets. Someembodiments may include more than two pieces of carbon fiber sheets forincreased strength. In some embodiments, carbon fiber sheets may beoriented in alternating layers of 0° orientation sheets and 45°orientation sheets.

The carbon fiber sheets can be, for example, those used in carbonfiber-reinforced plastic. In some embodiments, the carbon fiber sheetcan be a woven carbon fiber sheet. For example, the carbon fiber sheetsmay comprise one or more of 1K plain weave ultralight carbon fiberfabric, 3K plain weave carbon fiber fabric, 3K twill weave carbon fiber,or 12K carbon fiber of Fibreglast Developments Corporation. Any carbonfiber material may be used and woven in to the desired weave. Forexample, suitable carbon fiber materials provided by Toray include:Toray T300, Toray M46J, and/or Toray T800.

Additionally, graphitic powder may be added to the carbon fiber of thecarbon fiber-reinforced polymer. In some embodiments, addition ofgraphitic powder may increase the specific capacity as much as threetimes as that exhibited by just the carbon fiber.

The carbon fiber sheets may be aligned and placed on apolytetrafluoroethylene (PTFE) sheet. In some embodiments, the PTFEsheet may be placed on a piece of heat-resistant glass. The PTFE sheetand/or heat-resistant glass may provide a border around the carbon fibersheets on all sides. For example, the PTFE sheet and/or heat-resistantglass may provide a border of at least one centimeter around the stackedcarbon fiber sheets on all sides. The PTFE sheet may be any of variousshapes. For example, the PTFE sheet may be flat, or it may be of aconcave or a convex curve. In some embodiments, the carbon fiber sheetsmay be placed onto a flat or a curved PTFE sheet and applied to a curvedmold.

Metallic Battery Tabs: Some embodiments may include metallic batterytabs. For example, some embodiments of an electrode may include metallicbattery tabs that are in physical and/or electrical contact with thecarbon fiber of the carbon fiber-reinforced polymer sheets. In someembodiments, one or more metallic battery tabs may comprise aluminum,copper, nickel, and/or combinations thereof. For example, one or morealuminum battery tabs may be used for a cathode current collector. Insome embodiments, one or more copper and/or nickel battery tabs may beused for an anode current collector. An example of an aluminum batterytab that may be used is a 4 mm-width aluminum tab with adhesive polymertape (MTI Corporation). However, any suitable metallic tab may be used.

Various methods may be used to prevent the polymer from adhering to themetallic tabs or otherwise interfering with the contact between thecarbon fiber and metallic tab. In some embodiments, adhesive Kapton tapemay be placed on both sides of a metallic tab. After insertion of themetallic tab(s) and addition of a polymer, the tape may be removed fromthe metallic tab. In some embodiments, a tab may be inserted between twoor more carbon fiber sheets such that a 0.2-2 cm length of the tab isembedded within the carbon fiber sheets. In some embodiments, more than0.2 cm of metallic tab may be embedded within the carbon fiber sheets.In some embodiments, more than 0.3 cm, 0.4 cm, 0.5 cm, 0.6 cm, 0.7 cm,0.8 cm, 1.0 cm, 1.2 cm, 1.4 cm, 1.5 cm, 1.6 cm, or more than 1.8 cm ofmetallic tab may be in contact with the carbon fiber sheets. In someembodiments, less than 2.0 cm of metallic tab may be in contact with thecarbon fiber sheets. In some embodiments, less than 1.8 cm, 1.6 cm, 1.4cm, 1.2 cm, 1.0 cm, 0.8 cm, 0.7 cm, 0.6 cm, 0.5 cm, or less than 0.4 cmof metallic tab may be in contact with the carbon fiber sheets. In someembodiments, an exposed part of the metallic tab not between carbonfiber sheets may be covered with Kapton tape.

Epoxy/Polymer Preparation and Infiltration: The epoxy for the carbonfiber-reinforced polymer may be prepared using one or more severaldifferent ways known in the art. For example, the epoxy may be preparedsimilarly to any carbon fiber-reinforced plastic composite. In someembodiments, a two-part epoxy (comprising a resin and a hardener) may beused, such as the System 2000 Epoxy Resin (Fibre Glast DevelopmentsCorporation) or similar product. In some embodiments, a liquid acrylatemonomer may be used, along with an initiator chemical and heat. A liquidacrylate monomer may comprise ethoxylated (4) pentaerythritoltetraacrylate, tetraethylene glycol dimethacrylate, ethoxylated (30)bisphenol-A diacrylate, propoxylated (3) glyceryl triacrylate, methoxypolyethylene glycol (500) monoacrylate, and/or mixtures of any liquidmonomers. A comprehensive list of suitable monomers is provided inSnyder et al., Chemistry of Materials Volume 19, pages 3793-3801 (2007).An initiator chemical may be, for example, tert-butyl peroxide. In someembodiments, an initiator chemical may be mixed with a liquid monomer inan amount between 0.1 and 25 wt %. In some embodiments, the initiatorchemical may comprise more than 0.1 wt %, more than 0.5 wt %, more than1.0 wt %, more than 1.5 wt %, more than 2.0 wt %, more than 2.5 wt %,more than 3.0 wt %, more than 3.5 wt %, more than 4.0 wt %, more than4.5 wt %, more than 5.0 wt %, more than 5.5 wt %, more than 6.0 wt %,more than 6.5 wt %, more than 7.0 wt %, more than 7.5 wt %, more than8.0 wt %, more than 8.5 wt %, more than 9.0 wt %, more than 9.5 wt %,more than 10 wt %, more than 12 wt %, more than 15 wt %, more than 18 wt%, more than 20 wt %, or more than 22 wt % of the mixture. In someembodiments, the initiator chemical may comprise less than 25 wt %, lessthan 22 wt %, less than 20 wt %, less than 18 wt %, less than 15 wt %,less than 12 wt %, less than 10 wt %, less than 8 wt %, less than 6 wt%, less than 5 wt %, less than 4 wt %, less than 3.5 wt %, less than 3.0wt %, less than 2.5 wt %, less than 2.0 wt %, less than 1.5 wt %, lessthan 1.0 wt %, or less than 0.5 wt % of the mixture. In someembodiments, the initiator chemical may comprise between 0.1 and 5 wt %,between 1.0 and 4 wt %, or between 1.25 and 2 wt % of the mixture.

In some embodiments, the hardener in a resin-hardener mixture maycomprise between 9 wt % and 50 wt %. In some embodiments, the hardenermay comprise between 10 wt % and 40 wt %, between 15 wt % and 35 wt %,or between 20 wt % and 30 wt % of a resin-hardener mixture. The hardenermay comprise less than 50 wt %, less than 40 wt %, less than 30 wt %,less than 20 wt %, or less than 15 wt % of a resin-hardener mixture. Insome embodiments, the hardener of a resin-hardener mixture may comprisemore than 9 wt %, more than 15 wt %, more than 25 wt %, more than 35 wt%, or more than 45 wt % of a resin-hardener mixture.

In some embodiments, the resin-hardener mixture or monomer-initiatormixture is spread or poured over the carbon fiber layers to form alay-up (carbon fiber and epoxy assembly). Generally, between 10 and 100milligrams of a liquid mixture are required per square centimeter ofcarbon fiber sheet. Thus, if two carbon fiber sheets are used, between20 and 200 milligrams/cm² are required; if three carbon fiber sheets areused, between 30 and 300 milligrams/cm² are required, and so on. In someembodiments, more than 10 mg/cm² carbon sheet are required, more than 15mg/cm² carbon sheet, more than 20 mg/cm² carbon sheet, more than mg/cm²carbon sheet, more than 40 mg/cm² carbon sheet, more than 50 mg/cm²carbon sheet, more than mg/cm² carbon sheet, more than 70 mg/cm² carbonsheet, or more than 80 mg/cm² carbon sheet are required. In someembodiments, less than 100 mg/cm² carbon sheet, less than 90 mg/cm²carbon sheet, less than 80 mg/cm² carbon sheet, less than 70 mg/cm²carbon sheet, less than 60 mg/cm² carbon sheet, less than 50 mg/cm²carbon sheet, or less than 40 mg/cm² carbon sheet, less than 30 mg/cm²carbon sheet, or less than 20 mg/cm² carbon sheet are required. In someembodiments, between 15 and 90 mg/cm² carbon sheet, between 20 and 80mg/cm² carbon sheet, between 25 and 70 mg/cm² carbon sheet, between 25and 60 mg/cm² carbon sheet, or between 25 and 50 mg/cm² carbon sheet arerequired.

In some embodiments, once the carbon fiber sheet layers are infiltratedwith the resin-hardener mixture or monomer-initiator mixture, a secondPTFE sheet may be placed on top of the lay-up. In some embodiments, asecond glass plate is placed on top of the PTFE. Weights may then beplaced on top of this entire assembly to keep the layers flat. In someembodiments, a vacuum-bag system may be used to keep the carbon andepoxy pressed to the mold. For example, a vacuum-bag system may be usedfor assemblies comprising curved PTFE sheets and/or curved molds. Acurved mold may comprise fiberglass, plastic, or any other suitablematerial. For assemblies comprising a monomer-initiator mixture, theassembly may be placed in an oven at the desired temperature accordingto the chemical initiator used. The temperature is determined accordingto the initiator used. For example, an assembly comprising tert-butylacrylate may be placed in an oven at 140° C. for four hours.

After the required time of curing and/or heating, the fabricationmaterials (including glass plates, PTFE sheets, Kapton tape, and excesscured epoxy) may be removed from the current collector assembly. In someembodiments, one or more surfaces of the formed current collectorassembly may be abraded to expose the carbon fiber.

Abrasion of Carbon Fiber-reinforced Polymer: The surface of the carbonfiber-reinforced polymer, upon fabrication, is generally not conductive.The carbon fiber of the carbon fiber-reinforced polymer is conductive,however, and must be exposed for the carbon fiber-reinforced polymer toserve as an electrode. Once exposed, the conductivity of the carbonfiber-reinforced polymer may also be tested and verified.

Various methods may be used to abrade a surface of a current collectorassembly. In some embodiments, a surface of one side of a currentcollector may be sanded. For example, a surface of the assembly may besanded using an electric sander with 200- to 800-grit sandpaper. In someembodiments, scraping may be used to expose the carbon fiber of thecurrent collector assembly. Some embodiments may use chemical exposure.However, any abrasion method known in the art may be used to expose aportion of the carbon fiber of the carbon fiber-reinforced polymer.

In some embodiments, a side of the carbon fiber-reinforced polymer maybe scraped, sanded, or otherwise abraded to expose a portion of thecarbon fiber. This exposed carbon fiber may be oriented duringstructural battery fabrication such that it is in contact with anelectrolyte.

Surface Coating with Active Materials: The carbon fiber-reinforcedpolymer assembly may be used as an active material at an anode and as acurrent collector at one or both electrodes. In some embodiments, asurface of a carbon fiber-reinforced polymer current collector may becoated with one or more active materials to increase charge-storagecapacity. For example, a carbon fiber-reinforced polymer anode may becoated with graphite, silicon, mesoporous carbon microbeads, and/orlithium titanate on a conductive side. A carbon fiber-reinforced polymercathode may be coated with lithium cobalt oxide on a conductive side. Insome embodiments, a carbon fiber-reinforced polymer cathode may becoated with lithium cobalt oxide. Some embodiments of a carbonfiber-reinforced polymer cathode may include active materials such aslithium nickel-manganese-cobalt oxide and/or lithium iron phosphate.

Fabrication Methods and Techniques for Structural Batteries

Any of the electrodes previously disclosed herein can be incorporatedinto a structural battery. A structural battery can include at least twoelectrodes and at least one separator. In some embodiments, thestructural battery can include a liquid electrolyte or a gelelectrolyte.

Separator: In some embodiments, a structural battery can include atleast one separator between two or more electrodes. For example,separator material may include porous polyolefin film such as thatprovided by Celgard. In some embodiments, separator material may includeporous glass microfiber, such as products provided by Whatman®. In someembodiments, the separator may be glass, plastic, a polyolefin, and/or aporous polyolefin sheet. In some embodiments, the electrolyte may be agel electrolyte and a separator may not be necessary.

Structural batteries may be single-sided or double-sided. In someembodiments of a double-sided cell, the battery layers may be stacked inthe order of: a first carbon fiber-reinforced polymer anode, aseparator(s), a double-sided cathode coating, a separator(s), a carbonfiber-reinforced polymer anode. The conductive side of each carbon fiberanode should be in contact with its respective adjacent separator. Insome embodiments of a single-sided cell, the battery layers may bestacked in the order of: a first carbon fiber-reinforced polymer anode,a separator(s), a cathode coating on aluminum and/or carbon fiber.

In some embodiments, the components of the structural battery may beoriented in a stacked configuration. For example, a first electrode maybe placed on top of a separator, and the separator may be placed on topof a second electrode. In some embodiments, the components of thestructural battery may be oriented in a side-by-side configuration. Forexample, a first electrode, a separator, and a second electrode may eachbe placed adjacent to one another.

Some embodiments can use electrodes and separators of rectangular,circular, triangular, or other geometric shapes. The initial 2D shape ofthe components can be trivial and may be limited by the ability tomaintain the fiber weave of the carbon.

Once oriented, the multiple battery layers may be held togethertemporarily. Multiple battery layers may be temporarily bound togetherusing one or more clamps, clips, weights, or the like. In someembodiments, the carbon fiber-reinforced polymer may be engineered toact as a barrier to oxygen and water.

In some embodiments, the stacked multiple battery layers may be placedbetween layers of aluminum film to form a cell assembly. For example, apouch may be constructed using laminated aluminum film (MTICorporation). One or more pieces of aluminum film may be cut such thatthe film is large enough to provide a border around the carbonfiber-reinforced polymer assemblies. In some embodiments, the stackedbattery layers may be placed between two cut pieces of laminatedaluminum film. In some embodiments, the stacked battery layers may beplaced into a folded single piece of aluminum film, such that the verybottom layer and the very top layer of the aluminum film-battery layerassembly is the laminated aluminum film. In some embodiments, sides ofthe aluminum film may be sealed such that at least one side remainsopen. For example, three sides of a rectangular pouch may be sealed witha heated impulse sealer. However, any sealing tool known in the art maybe used.

A cell assembly may be treated in an oven and an unheated antechamber.In some embodiments, a cell assembly may be treated in a heatedantechamber. Both methods of treatment are described in detail below.

A cell assembly may be placed in an oven. In some embodiments, the cellassembly may be heated in an oven for between 15 minutes and 120minutes. The cell assembly may be heated for more than 15 minutes, morethan 30 minutes, more than 45 minutes, more than 60 minutes, more than75 minutes, more than 90 minutes, or more than 105 minutes. The cellassembly may be heated in an oven for less than 120 minutes, less than105 minutes, less than 90 minutes, less than 75 minutes, less than 60minutes, less than 45 minutes, or less than 30 minutes. In someembodiments, the cell assembly may be heated for between 15 minutes and105 minutes, between 30 minutes and 90 minutes, between 45 minutes and75 minutes, or between 55 minutes and 65 minutes.

The cell assembly may be heated in an oven at a temperature between 100°C. and 200° C. The cell assembly may be heated in an oven at atemperature greater than 100° C., greater than 110° C., greater than120° C., greater than 130° C., greater than 150° C., greater than 160°C., greater than 175° C., or greater than 190° C. The cell assembly maybe heated in an oven for less than 200° C., less than 180° C., less than160° C., less than 150° C., less than 140° C., less than 125° C., orless than 110° C. In some embodiments, the cell assembly may be heatedin an oven at a temperature between 100° C. and 180° C., between 100° C.and 150° C., or between 110° C. and 130° C.

The cell assembly may be transferred from an oven to an unheatedantechamber of a dry box (i.e. glove box). The unheated antechamber maycomprise argon gas. In some embodiments, the cell assembly may be placedunder vacuum in the glove box, for example, for between 10 and 24 hours.The cell assembly may be placed under vacuum for more than 10 hours,more than 12 hours, more than 14 hours, more than 15 hours, more than 16hours, more than 18 hours, more than 20 hours, or more than 22 hours. Insome embodiments, the cell assembly may be placed under vacuum for lessthan 24 hours, less than 22 hours, less than 20 hours, less than 18hours, less than 16 hours, less than 15 hours, less than 14 hours, orless than 12 hours. In some embodiments, the cell assembly may be placedunder vacuum for between 12 and 22 hours, between 12 and 20 hours,between 14 and 20 hours, or between 16 and 18 hours. In someembodiments, after being under vacuum in a glove box, the cell assemblymay be placed in a dry box.

The cell assembly may be placed in a heated antechamber of a dry box forbetween 10 and 24 hours. In some embodiments, the cell assembly may beplaced a heated antechamber for more than 10 hours, more than 12 hours,more than 14 hours, more than 15 hours, more than 16 hours, more than 18hours, more than 20 hours, or more than 22 hours. In some embodiments,the cell assembly may be placed in a heated antechamber for less than 24hours, less than 22 hours, less than 20 hours, less than 18 hours, lessthan 16 hours, less than 15 hours, less than 14 hours, or less than 12hours. In some embodiments, the cell assembly may be placed in a heatedantechamber for between 12 and 22 hours, between 12 and 20 hours,between 14 and 20 hours, or between 16 and 18 hours.

The cell assembly may be placed in a heated antechamber of a dry box ata temperature between 100° C. and 200° C. The heated antechamber maycomprise argon gas. In some embodiments, the cell assembly may be heatedin an oven at a temperature greater than 100° C., greater than 110° C.,greater than 120° C., greater than 130° C., greater than 150° C.,greater than 160° C., greater than 175° C., or greater than 190° C. Thecell assembly may be heated in an oven for less than 200° C., less than180° C., less than 160° C., less than 150° C., less than 140° C., lessthan 125° C., or less than 110° C. In some embodiments, the cellassembly may be heated in an oven at a temperature between 100° C. and180° C., between 100° C. and 150° C., or between 110° C. and 130° C.After being treated in a heated antechamber of a dry box, the cellassembly may be transferred to a dry box.

After a cell assembly has been treated in an antechamber of a dry box,an electrolyte solution may be added to the cell assembly. Anelectrolyte solution may be dispensed into the pouch with a pipette, forexample. In some embodiments, the amount of electrolyte to be dispensedmay be an amount between 25 and 150 μL per square centimeter. In someembodiments, the amount of electrolyte to be dispensed may be greaterthan 25 μL per square centimeter, greater than 50 μL per squarecentimeter, greater than 75 μL per square centimeter, greater than 100μL per square centimeter, greater than 125 μL per square centimeter,greater than 150 μL per square centimeter, or greater than 175 μL persquare centimeter. In some embodiments, the amount of electrolyte to bedispensed may be less than 200 μL per square centimeter, less than 175μL per square centimeter, less than 150 μL per square centimeter, lessthan 125 μL per square centimeter, less than 100 μL per squarecentimeter, less than 75 μL per square centimeter, or less than 50 μLper square centimeter. The amount of electrolyte to be dispensed may bebetween 25 and 125 μL per square centimeter, between 50 and 100 μL persquare centimeter, between 50 and 75 μL per square centimeter, orbetween 75 and 100 μL per square centimeter.

After an electrolyte is added to the cell assembly, any remainingopening sides of the aluminum pouch may be heat-sealed. Any remainingopening sides of the aluminum pouch may be sealed while the cellassembly is still in the dry box. In some embodiments, a heat impulsesealer may be used to seal any opening sides of the aluminum pouch.However, any sealing tool known in the art may be used.

Alternately, an impermeable coating or sealant may be used instead ofthe laminated aluminum film pouch. For example, the impermeable coatingor sealant is applied in the dry box to all but two small locations onthe outer surfaces of the battery cell assembly. The coating/sealant isthen allowed to cure. The electrolyte solution may be dispensed into thebattery cell through one of the unsealed locations. Gas from any deadspace in the battery cell may escape through the other unsealedlocation. The impermeable coating or sealant may then be applied to thetwo unsealed locations and allowed to cure such that the entire batterycell is sealed.

The sealed structural battery cell is removed from the dry box forelectrochemical testing.

Electrolyte: The structural batteries according to embodiments describedherein may include a liquid electrolyte. In some embodiments, the liquidelectrolyte can be an ionic liquid. A liquid electrolyte may be added tothe structural battery assembly within an argon-rich environment. Forexample, the structural battery assembly may be placed in a glove box ordry box comprising argon gas. A liquid electrolyte may be added to thealuminum pouch and allowed to infiltrate the structural batteryassembly.

In some embodiments, a gel electrolyte may be used. For example, a gelelectrolyte may include a combination of a polymer and a liquidelectrolyte. A polymer of a gel electrolyte may be poly(ethylene oxide),polyethylene glycol, or another suitable polymer for gel electrolytes.

Various types of liquid electrolytes may be used (for both a liquidelectrolyte and/or a gel electrolyte comprising a liquid electrolyte).In some embodiments, the liquid electrolyte solution may comprise a saltand a solvent. The salt of the liquid electrolyte solution may belithium hexafluorophosphate. The salt may also be lithiumtetrafluoroborate, lithium perchlorate, lithiumbis(trifluoromethylsulfonyl)imide, lithium trifluoromethanesulfonate. Insome embodiments, the solvent may be a mixture of ethylene carbonate andethyl methyl carbonate. The solvent may also comprise mixtures ofethylene carbonate, propylene carbonate, dimethyl carbonate, and/ordiethyl carbonate.

In some embodiments, the liquid electrolyte solution may be one molarlithium hexafloraphosphate dissolved in a mixture of ethylene carbonateand ethyl methyl carbonate. The electrolyte solution may comprise amixture of a lithium salt with ionic liquid such as1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide.

In some embodiments, a liquid electrolyte and/or gel electrolyte caninfiltrate the separator layer(s) and the electrodes rather than being aseparate layer itself. For example, the liquid electrolyte and/or gelelectrolyte may get into a vast majority of the crevices and voids ofthe electrodes and/or separators.

The electrolyte may comprise about 5-90%, about 10-80%, about 20-70%,about 30-60%, about 30-50%, about 35-45%, or about 40% of the totalstructural battery weight. In some embodiments, liquid electrolyte maycomprise no more than 40%, no more than 30%, no more than 20%, no morethan 15%, no more than 10%, no more than 5%, or no more than 2% of thetotal structural battery weight. In some embodiments, liquid electrolytemay comprise no less than 1%, no less than 3%, no less than 5%, no lessthan 10%, no less than 15%, no less than 20%, no less than 30%, or noless than 35% of the total structural battery weight.

Fabrication Sequencing: The structural batteries described herein can beelectrically stacked in series and/or in parallel. The structuralbatteries described herein can be mechanically layered in series and/orin parallel. In addition, one electrode for a first battery can be usedas an electrode for a second battery in series and/or in parallel. Thespecific battery components and fabrication sequencing explored above isnot intended to be exhaustive. A person having ordinary skill in the artcan readily identify other component and sequencing combinations ofwhich are meant to be covered by the disclosure herein.

Properties: The structural batteries disclosed herein can have aspecific energy of at least 0.02, at least 0.05, at least 0.1, at least0.15, at least 2.0, at least 2.5, at least 3.0, at least 3.5, at least4.0, at least 5.0, or at least 10.0 Wh/kg. In some embodiments, thestructural batteries disclosed herein can have a specific energy between0.05 and 0.40, between 0.1 and 0.35, or between 0.1 and 0.3 Wh/kg. Thestructural batteries disclosed herein can have a flexural strength of atleast 20, at least 30, at least 35, at least 40, at least 45, at least50, at least 55, at least 60, or at least 100 MPa. In some embodiments,the structural batteries disclosed herein can have a flexural strengthbetween 20-100, 30-90, 40-80, or 50-70 MPa. The structural batteriesdisclosed herein can have a flexural modulus of at least 0.5, at least1, at least 1.5, at least 2, at least 2.5, at least 3, at least 3.5, atleast 4, at least 5, or at least 10 GPa. In some embodiments, thestructural batteries disclosed herein can have a flexural modulusbetween 0.5 and 10 GPa, between 1 and 8 GPa, or between 2.5 and 5 GPa.

EXAMPLES

The following are example structural batteries and tests of examplestructural batteries conducted by Applicants.

The structural battery may be tested with a galvanostat or batterycycler. Galvanostatic cycling may be performed on the cell at a currentdensity of 0.2 to 1.0 milliamps per square-centimeter of cell area. Anupper voltage limit of 4.2 V and a lower voltage limit of 3.0 V may beused during the galvanostatic cycling. The battery may be charged anddischarged for at least 10 cycles. The resulting capacity and voltagevalues can be used to calculate specific capacity, specific energy, andcoulombic efficiency over multiple cycles.

FIGS. 13A-13C provide galvanostatic charge-discharge cycling data forcells according to some embodiments described herein. The results oftesting were normalized to accommodate variations in total cell weight.Specifically, FIG. 13A shows data for single-sided cells anddouble-sided cells. Five replicate double-sided cells were tested with acurrent density of 0.8 mA/cm². Four replicate single-sided cells weretested with a current density of 0.4 mA/cm². The graph of FIG. 13A showsthe specific energy (Wh/kg) of the cells over 10 charge-dischargecycles.

FIG. 13B shows data from a double-sided cell having a carbonfiber-reinforced polymer anode with a surface coating and 0.8 mA/cm²current density. Specifically, the graph shows the cell voltage (V) ofthe double-sided cell over a period of approximately 11 hours ofgalvanostatic charge-discharge cycling.

FIG. 13C provides data for a single-sided cell having a carbonfiber-reinforced polymer anode with a surface coating and 0.4 mA/cm²current density. Specifically, the graph shows cell voltage (V) of thesingle-sided cell over a period of approximately 11 hours ofgalvanostatic charge-discharge cycling.

FIGS. 14A-14C show data of galvanostatic charge-discharge cycling fortwo embodiments of double-sided cells. The results of testing werenormalized to accommodate variations in total cell weight. In FIG. 14A,the circular data points represent data from five replicate double-sidedcells having a carbon fiber-reinforced polymer anode with a graphiticsurface coating. The triangular data points represent data from threereplicate double-sided cells having a carbon fiber-reinforced polymeranode with no surface coating. The current density of both double-sidedcells was tested at 0.8 mA/cm². The graph of FIG. 14A shows the specificenergy (Wh/kg) of the cells over a series of 10 charge-discharge cycles.

FIG. 14B shows data from a double-sided cell having a carbonfiber-reinforced polymer anode with a graphitic surface coating and 0.8mA/cm² current density. Specifically, the graph shows the cell voltage(V) of the double-sided cell over a period of approximately 11 hours ofgalvanostatic charge-discharge cycling.

FIG. 14C shows data from a double-sided cell having a carbonfiber-reinforced polymer anode without a surface coating and 0.8 mA/cm²current density. Specifically, the graph shows the cell voltage (V) ofthe double-sided cell over a period of approximately 11 hours ofgalvanostatic charge-discharge cycling.

FIG. 15A provides the stress and strain behavior of a structuralelectrode according to any one or more of the embodiments describedherein, a structural battery according to any one or more of theembodiments described herein, and a structural supercapacitor. They-axis represents the flexural strength (psi) and the x-axis representsthe flexural strain (in/in) of the energy storage devices.

FIG. 15B shows the flexural strength (MPa) of a structuralsupercapacitor, a structural battery according to any one or more of theembodiments described here, and a sample of acrylonitrile butadienestyrene (ABS) plastic.

FIG. 15C shows the elastic modulus (GPa) of a structural supercapacitor,a structural battery according to Liu et al (Design and Fabrication ofmultifunctional structural batteries, 189 J. of Power Sources 1, 646(2009)), a structural battery according to any one or more of theembodiments described herein, and ABS plastic.

This application discloses several numerical ranges in the text andfigures. The numerical ranges disclosed inherently support any range orvalue within the disclosed numerical ranges even though a precise rangelimitation is not stated verbatim in the specification because thisdisclosure can be practiced throughout the disclosed numerical ranges.

The above description is presented to enable a person skilled in the artto make and use the disclosure, and is provided in the context of aparticular application and its requirements. Various modifications tothe preferred embodiments will be readily apparent to those skilled inthe art, and the generic principles defined herein may be applied toother embodiments and applications without departing from the spirit andscope of the disclosure. Thus, this disclosure is not intended to belimited to the embodiments shown, but is to be accorded the widest scopeconsistent with the principles and features disclosed herein.

The invention claimed is:
 1. An electrode for a structural batterycomprising: one or more carbon fiber sheets; one or more metallic tabsembedded between layers of the one or more carbon fiber sheets; and apolymer, wherein the electrode is shaped as at least a portion of afunctional component of a device to which the structural batteryprovides energy when incorporated into the device such that theelectrode forms the at least a portion of the functional component ofthe device, wherein the functional component comprises one or more of acomponent of: a wing, a boom, a body, a chassis, or a door of a device.2. The electrode of claim 1, wherein the at least a portion of thefunctional component comprises an exterior surface of the device.
 3. Theelectrode of claim 2, wherein the exterior surface of the device isfunctional.
 4. The electrode of claim 2, wherein the exterior surface isconfigured to increase the aerodynamic performance of the device.
 5. Theelectrode of claim 1, wherein the device is a ground vehicle or anaerial vehicle.
 6. The electrode of claim 1, wherein the one or moremetallic tabs embedded between layers of the carbon fiber sheetscomprise a first portion embedded between the one or more carbon fibersheets and a second portion extending outwardly from the one or morecarbon fiber sheets.
 7. The electrode of claim 1, further comprising asurface coating comprising an active material.
 8. The electrode of claim7, wherein the active material comprises one or more of graphite,silicon, mesoporous carbon microbeads, lithium titanate, lithium cobaltoxide, lithium nickel-manganese-cobalt oxide, or lithium iron phosphate.9. The electrode of claim 1, wherein the one or more metallic tabscomprises aluminum, copper, or nickel.
 10. The electrode of claim 1,wherein an edge is abraded using physical abrasion or chemical abrasionto expose a portion of the carbon fiber of the electrode.
 11. Theelectrode of claim 1, wherein the polymer comprises a liquid acrylatemonomer and an initiator.
 12. The electrode of claim 11, wherein theinitiator comprises tert-butyl peroxide.
 13. The electrode of claim 11,wherein the liquid acrylate monomer comprises ethoxylated (4)pentaerythritol tetraacrylate, tetraethylene glycol dimethacrylate,ethoxylated (30) bisphenol-A diacrylate, propoxylated (3) glyceryltriacrylate, methoxy polyethylene glycol (500) monoacrylate, or anycombination thereof.
 14. The electrode of claim 11, wherein theinitiator comprises more than 0.1 wt % of an initiator-liquid monomermixture.
 15. The electrode of claim 11, wherein the initiator comprisesless than 5 wt % of an initiator-liquid monomer mixture.
 16. Theelectrode of claim 1, wherein the polymer comprises a resin and ahardener.